US3106674A - Regulator protection circuits - Google Patents

Regulator protection circuits Download PDF

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Publication number
US3106674A
US3106674A US75972A US7597260A US3106674A US 3106674 A US3106674 A US 3106674A US 75972 A US75972 A US 75972A US 7597260 A US7597260 A US 7597260A US 3106674 A US3106674 A US 3106674A
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transistor
potential
impedance means
load
source
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Expired - Lifetime
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US75972A
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Billy H Hamilton
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to NL272107D priority Critical patent/NL272107A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US75972A priority patent/US3106674A/en
Priority to DEW31116A priority patent/DE1165743B/en
Priority to JP4351961A priority patent/JPS4216379B1/ja
Priority to FR881192A priority patent/FR1308842A/en
Priority to CH1440761A priority patent/CH388443A/en
Priority to BE611498A priority patent/BE611498A/en
Priority to GB44746/61A priority patent/GB1009205A/en
Application granted granted Critical
Publication of US3106674A publication Critical patent/US3106674A/en
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
    • G05F1/569—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection
    • G05F1/573—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection with overcurrent detector

Definitions

  • a fuse in series with the circuit output.
  • a fuse has an inherent time lag which extends from the instant of overload to the time it finally blows. Since the energy stored in the input filter capacitor appears instantaneously across the transistor collector-emitter electrodes when an output short occurs, the time lag of the fuse is such that the transistor would be damaged.
  • a feature of this invention resides in the use of a voltage divider to predetermine the charge on a capacitor which is bridged across the series regulating transistor together with a series diode, the diode being normally backbiased in such manner that the capacitor does not interfere with the operation of the regulating transistor.
  • FIGURE of which is a schematic view of a series voltage regulator embodying the present invention.
  • PNP transistors 1 and 11 As shown in the drawing, there are provided PNP transistors 1 and 11, a Zener asymmetrical-1y conducting device 10, an asymmetrically conducting device 3, a fuse 4, capacitors 2 and 7, and alternating-current source '9, a full-wave rectifier bridge 8, resistors 5, 6, 12 and 16 and an adjustable resistor 13. Terminals 1'4 and 15 are output terminals.
  • the input alternating-current source 9 is connected to the input of the full-wave rectifier bridge 8.
  • Filter oapacitor 7 is connected across the output of the bridge 8.
  • a voltage divider comprising resistors 5 and 6 is connected across the filter capacitor 7.
  • Fuse 4 is connected between one terminal of the output of bridge 8 and the output terminal 14.
  • the collector-emitter electrodes of transistor '1 are serially connected between the output terminal of the bridge 8 and output terminal 15.
  • Capacitor 2 and asymmetrically conducting device 3 are serially connected across the collector-emitter electrodes of transistor 1.
  • the junction of capacitor 2 and asymmetrically conducting device 3 is connected to the junction of resistors '5 and 6.
  • Zener asymmetrically conducting device 10 and resistor 12 are serially connected across output terminals 14 and 15 as is adjustable resistor 13.
  • the collector of transistor 11 is connected to the base of transistor 1.
  • the emitter of transistor 11 is connected to the junction of Zener asymmetrically conducting device 10 and resistor 12.
  • Resistor 16 is connected across the base-collector electrodes of transistor 1.
  • the operation of the regulator can be described as follows: If the output voltage across terminals 14 and 15 should become less positive with respect to its normal operating level a portion of this less positive charge determined by adjustable resistor 13 is compared with the standard voltage of Zener asymmetrically conducting device 10 which, in turn, biases the base-emitter junction of transistor 11 such as to decrease the collector-emitter current flow of transistor 11. Decreased current flow through the collector-emitter path of transistor 11 results in increased current flow out of the base of transistor 1, thus biasing transistor 1 further into conduction which, in turn, results in greater emitter-collector current flow through transistor I.
  • the potential stored in input filter capacitor 7 is of the same magnitude as the potential appearing across the output terminals of the bridge rectifier 8.
  • the magnitude of the potential stored in capacitor 2 is determined by the voltage divider comprising resistors 5 and 6 and is thus intermediate to the potential appearing across capacitor 7.
  • the charge on capacitor 2 is of the polarity shown on the drawing, from which it is readily seen that conventional asymmetrically conducting device 3 is backbiased under normal operating conditions.
  • a voltage variation protected regulator circuit comprising first variable impedance means for controlling the current flowing from an unregulated source of potential to a load, passive impedance means including a diode which is forward biased in the event of variations in said unregulated source of potential or across said load to protect said variable impedance means, means for connecting said passive impedance means across said first impedance means, and means for reverse biasing said passive impedance means with a portion of the unregulated potential of said unregulated source of potential whereby said first impedance means is protected from input and output voltage variations due to input source or load malfunctions or characteristics.
  • a voltage regulator which includes a source of direct potential, a load, and a regulating transistor having its emitter-coilector path connected in series between said source and said load, an arrangement for protecting said transistor against damage during at least transient short-circuited load conditions which comprises a net- Work consisting of a capacitor and a diode connected in series with one another directly between the emitter and collector electrodes of said t-nansistor, said diode being poled in the direction of current flow through said load from said source, and means to bias said diode in the reverse direction by a potential less than the potential of said source.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)
  • Dc-Dc Converters (AREA)
  • Protection Of Static Devices (AREA)

Description

Oct. 8, 1963 B. H. HAMILTON REGULATOR PROTECTION CIRCUITS Filed Dec. 15, 1960 I/Vl/EN 70/? B. H. HAM/L TON BY Kym ATTORNEY United States Patent Ofi 3,1 06,6 74 Patented Oct. 8, 1963 ice 3,106,674 REGULATOR PROTECTION CIRCUITS Billy H. Hamilton, Summit, N.J., assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York Filed Dec. 15, 1960, Ser. No. 75,972 3 Claims. (Cl. 323-22) This invention relates to voltage and more specifically to protection tors.
In the series transistor regulators taught by the prior art, see for example United States Patent 2,751,549, if the output terminals should accidentally become shorted the energy stored in the input filter capacitor will instantaneously appear across the collector and emitter electrodes of the series regulating transistor. The magni tude of the voltage thus impressed across the transistor collector-e-miter electrodes usually exceeds the maximum normal transistor opera-ting voltage and causes permanent damage to the transistor.
The obvious solution to the problem appears to require the insertion of a fuse in series with the circuit output. A fuse, however, has an inherent time lag which extends from the instant of overload to the time it finally blows. Since the energy stored in the input filter capacitor appears instantaneously across the transistor collector-emitter electrodes when an output short occurs, the time lag of the fuse is such that the transistor would be damaged.
I has been found that this disadvantage may be overcome by placing a capacitor across the transistor collec tor-emitter electrodes in series with the fuse. With this arrangement, if an accidental short should occur across the output terminals, the capacitor would limit the rate of voltage rise across the transistor collector-emitter terminals and at the same time blow the fuse to effectively remove the output trouble condition. The presence of the capacitor, however, results in the serious operating disadvantage of interfering with the normal regulating function of the transistor to absorb both a fast input voltage change and the high frequency components of ripple It has also been found that the collector-emitter electrodes of the series regulating transistor may be protected by bridging them with a Zener diode rated for breakdown at a voltage slightly higher than the maximum normal voltage drop across the collector-emitter electrodes. The Zener diode does not interfere with the normal regulating functions of the transistor. However, since Zener diodes with power ratings sufiicient to withstand peak surge power are not readily available this method is limited.
It is therefore an object of this invention to provide a regulator protection circuit Which does not interfere with normal regulating features.
It is a further object of this invention to provide a regulator protection circuit which comprises readily available components.
It has been found that these objectives may be achieved by employing a capacitor back-biased diode combination bridged across the collector-emitter terminals of the series regulating transistor.
A feature of this invention resides in the use of a voltage divider to predetermine the charge on a capacitor which is bridged across the series regulating transistor together with a series diode, the diode being normally backbiased in such manner that the capacitor does not interfere with the operation of the regulating transistor.
Other objects and features of the present invention will become apparent upon consideration of the following detailed description and the accompanying drawing, the
and current regulators circuits for said regulasingle FIGURE of which is a schematic view of a series voltage regulator embodying the present invention.
As shown in the drawing, there are provided PNP transistors 1 and 11, a Zener asymmetrical-1y conducting device 10, an asymmetrically conducting device 3, a fuse 4, capacitors 2 and 7, and alternating-current source '9, a full-wave rectifier bridge 8, resistors 5, 6, 12 and 16 and an adjustable resistor 13. Terminals 1'4 and 15 are output terminals.
The input alternating-current source 9 is connected to the input of the full-wave rectifier bridge 8. Filter oapacitor 7 is connected across the output of the bridge 8. A voltage divider comprising resistors 5 and 6 is connected across the filter capacitor 7. Fuse 4 is connected between one terminal of the output of bridge 8 and the output terminal 14. The collector-emitter electrodes of transistor '1 are serially connected between the output terminal of the bridge 8 and output terminal 15. Capacitor 2 and asymmetrically conducting device 3 are serially connected across the collector-emitter electrodes of transistor 1. The junction of capacitor 2 and asymmetrically conducting device 3 is connected to the junction of resistors '5 and 6. Zener asymmetrically conducting device 10 and resistor 12 are serially connected across output terminals 14 and 15 as is adjustable resistor 13. The collector of transistor 11 is connected to the base of transistor 1. The emitter of transistor 11 is connected to the junction of Zener asymmetrically conducting device 10 and resistor 12. Resistor 16 is connected across the base-collector electrodes of transistor 1.
The operation of the regulator can be described as follows: If the output voltage across terminals 14 and 15 should become less positive with respect to its normal operating level a portion of this less positive charge determined by adjustable resistor 13 is compared with the standard voltage of Zener asymmetrically conducting device 10 which, in turn, biases the base-emitter junction of transistor 11 such as to decrease the collector-emitter current flow of transistor 11. Decreased current flow through the collector-emitter path of transistor 11 results in increased current flow out of the base of transistor 1, thus biasing transistor 1 further into conduction which, in turn, results in greater emitter-collector current flow through transistor I. (The current through biasing resistor 16 does not change appreciably.) Increased current flow through the emitter-collector path of transistor 1 results in increased current flow through the load connected to the output terminals 14 and 15, thus compensating for the original less positive change across output terminals 14 and 15.
The potential stored in input filter capacitor 7 is of the same magnitude as the potential appearing across the output terminals of the bridge rectifier 8. The magnitude of the potential stored in capacitor 2 is determined by the voltage divider comprising resistors 5 and 6 and is thus intermediate to the potential appearing across capacitor 7. The charge on capacitor 2 is of the polarity shown on the drawing, from which it is readily seen that conventional asymmetrically conducting device 3 is backbiased under normal operating conditions.
If the output terminals 14 and 15 were to become accidentally shorted in a regulator structure wherein capacitor 2, asymmetrically conducting device 3, and resistors 5 and 6 are not employed, the potential stored in input filter capacitor 7 would instantaneously appear across the collector-emitter electrodes of series regulating transistor 1 causing, as heretofore noted, permanent transistor damage. In the configuration of the present invention, it is apparent that in the event of accidental shorting of output terminals 14 and 15 the charge on capacitor 7 will bias asymmetrically conducting device 3 into conduction and thereby permit capacitor 2 to slowly begin to charge to the higher potential of capacitor '7. The period of time required for capacitor 2 to charge to the higher potential is many times greater than the period of time required for fuse 4- to blow and open the circuit to effectively remove the trouble condition. In a similar manner the collector-emitter electrodes of transistor 1 are also protected from transients which occur during the initial turn-on of the circuit. Voltage transients at turnon are occasioned by the presence of capacitance in the load circuit.
it should be understood that combinations of NPN and PNP transistors other than those shown may be used equally as etfectively.
Since changes may be made in the above-described arrangement and different embodiments may be devised by those skilled in the art without departing from the spirit and scope of the invention, it is to be understood that all matter contained in the foregoing description and accompanying drawing is illustrative of the application of the principles of the invention and is not to be construed in a limiting sense.
What is claimed is:
1. A voltage variation protected regulator circuit comprising first variable impedance means for controlling the current flowing from an unregulated source of potential to a load, passive impedance means including a diode which is forward biased in the event of variations in said unregulated source of potential or across said load to protect said variable impedance means, means for connecting said passive impedance means across said first impedance means, and means for reverse biasing said passive impedance means with a portion of the unregulated potential of said unregulated source of potential whereby said first impedance means is protected from input and output voltage variations due to input source or load malfunctions or characteristics.
2. In a voltage regulator which includes a source of direct potential, a load, and a regulating transistor having its emitter-coilector path connected in series between said source and said load, an arrangement for protecting said transistor against damage during at least transient short-circuited load conditions which comprises a net- Work consisting of a capacitor and a diode connected in series with one another directly between the emitter and collector electrodes of said t-nansistor, said diode being poled in the direction of current flow through said load from said source, and means to bias said diode in the reverse direction by a potential less than the potential of said source.
3. In a voltage regulator which includes a source of direct potential, a load, a regulating transistor having its emitter-collector path connected in series between said source and said load, and a fuse connected to carry the current flowing from said load to said source, an arrangement for protecting said transistor against damage firom short-circuited load conditions which comprises a network consisting of :a capacitor and a diode connected in series with one another directly between the emitter and collector electrodes of said transistor, said diode being poled in the direction of curnent flow through said load from said source, and means to bias said diode in the reverse direction by a potential less than the potential of said source, whereby said network bypasses said transistor during transient sl1ort-circuited load conditions and bypasses said transistor until said fuse blows during persisting shont=circuited load conditions.
References Cited in the file of this patent UNITED STATES PATENTS 2,904,742- Ch-ase Sept. 15, 1959 2,922,945 Norris et a1. Ian. 26, 1960 2,925,548 Scherer Feb. 16, 1960 2,967,991 Deuitch Jan. 10. 1961

Claims (1)

1. A VOLTAGE VARIATION PROTECTED REGULATOR CIRCUIT COMPRISING FIRST VARIABLE IMPEDANCE MEANS FOR CONTROLLING THE CURRENT FLOWING FROM AN UNREGULATED SOURCE OF POTENTIAL TO A LOAD, PASSIVE IMPEDANCE MEANS INCLUDING A DIODE WHICH IS FORWARD BIASED IN THE EVENT OF VARIATIONS IN SAID UNREGULATED SOURCE OF POTENTIAL OR ACROSS SAID LOAD TO PROTECT SAID VARIABLE IMPEDANCE MEANS, MEANS FOR CONNECTING SAID PASSIVE IMPEDANCE MEANS ACROSS SAID FIRST IMPEDANCE MEANS, AND MEANS FOR REVERSE BIASING SAID PASSIVE IMPEDANCE MEANS WITH A PORTION OF THE UNREGULATED POTENTIAL OF SAID UNREGULATED SOURCE OF PONTENTIAL WHREBY SAID FIRST IMPEDANCE MEANS IS PROTECTED FROM INPUT AND OUTPUT VOLTAGE VARIATIONS DUE TO INPUT SOURCE OR LOAD MALFUNCTIONS OR CHARACTERISTICS.
US75972A 1960-12-15 1960-12-15 Regulator protection circuits Expired - Lifetime US3106674A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
NL272107D NL272107A (en) 1960-12-15
US75972A US3106674A (en) 1960-12-15 1960-12-15 Regulator protection circuits
DEW31116A DE1165743B (en) 1960-12-15 1961-11-22 Controller protection circuit
JP4351961A JPS4216379B1 (en) 1960-12-15 1961-12-05
FR881192A FR1308842A (en) 1960-12-15 1961-12-06 Protection circuits for regulator
CH1440761A CH388443A (en) 1960-12-15 1961-12-12 Electric current regulator
BE611498A BE611498A (en) 1960-12-15 1961-12-13 Regulator protective circuit
GB44746/61A GB1009205A (en) 1960-12-15 1961-12-14 Voltage and current regulators

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Application Number Priority Date Filing Date Title
US75972A US3106674A (en) 1960-12-15 1960-12-15 Regulator protection circuits

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US3106674A true US3106674A (en) 1963-10-08

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JP (1) JPS4216379B1 (en)
BE (1) BE611498A (en)
CH (1) CH388443A (en)
DE (1) DE1165743B (en)
FR (1) FR1308842A (en)
GB (1) GB1009205A (en)
NL (1) NL272107A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3192405A (en) * 1962-04-19 1965-06-29 Honeywell Inc Diode bias circuit
US3207950A (en) * 1962-10-15 1965-09-21 Eaton Mfg Co Control for electrical coupling apparatus
US3323035A (en) * 1964-02-06 1967-05-30 Forbro Design Corp Transistor regulated power supply leakage current supply
US3334241A (en) * 1964-05-13 1967-08-01 Bell Telephone Labor Inc Stabilized transistor regulator
US3461376A (en) * 1966-02-14 1969-08-12 Wanlass Electric Co Ac solid state voltage regulator
US3546494A (en) * 1966-07-28 1970-12-08 Wanlass Electric Co Dynamic filter
US4459630A (en) * 1982-08-27 1984-07-10 Honeywell, Inc. Excess current protection circuit for a power supply

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2904742A (en) * 1957-09-16 1959-09-15 Bell Telephone Labor Inc Current supply apparatus
US2922945A (en) * 1956-03-30 1960-01-26 Itt Transistorized voltage regulators
US2925548A (en) * 1958-02-10 1960-02-16 Sorensen & Company Inc Protective device for transistor regulators
US2967991A (en) * 1957-01-08 1961-01-10 Rca Corp Power supply

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL103572C (en) * 1956-10-12
DE1063696B (en) * 1957-12-20 1959-08-20 Siemens Ag Protection circuit against overcurrent for AC circuits
DE1072714B (en) * 1958-02-13 1960-01-07 Westinghouse Electric Corporation, East Pittsburgh, Pa. (V. St. A.) Power supply protection circuit
DE1084820B (en) * 1959-07-14 1960-07-07 Licentia Gmbh Short-circuit protection circuit for transistor power supplies

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2922945A (en) * 1956-03-30 1960-01-26 Itt Transistorized voltage regulators
US2967991A (en) * 1957-01-08 1961-01-10 Rca Corp Power supply
US2904742A (en) * 1957-09-16 1959-09-15 Bell Telephone Labor Inc Current supply apparatus
US2925548A (en) * 1958-02-10 1960-02-16 Sorensen & Company Inc Protective device for transistor regulators

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3192405A (en) * 1962-04-19 1965-06-29 Honeywell Inc Diode bias circuit
US3207950A (en) * 1962-10-15 1965-09-21 Eaton Mfg Co Control for electrical coupling apparatus
US3323035A (en) * 1964-02-06 1967-05-30 Forbro Design Corp Transistor regulated power supply leakage current supply
US3334241A (en) * 1964-05-13 1967-08-01 Bell Telephone Labor Inc Stabilized transistor regulator
US3461376A (en) * 1966-02-14 1969-08-12 Wanlass Electric Co Ac solid state voltage regulator
US3546494A (en) * 1966-07-28 1970-12-08 Wanlass Electric Co Dynamic filter
US4459630A (en) * 1982-08-27 1984-07-10 Honeywell, Inc. Excess current protection circuit for a power supply

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Publication number Publication date
FR1308842A (en) 1962-11-09
NL272107A (en) 1900-01-01
JPS4216379B1 (en) 1967-09-05
BE611498A (en) 1962-03-30
DE1165743B (en) 1964-03-19
CH388443A (en) 1965-02-28
GB1009205A (en) 1965-11-10

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